Hot water heating systems are known. A common system used in North America includes a large water storage tank which has means for heating the water in the tank prior to discharge, for example to a sink, washing machine or the like. The water in such storage tanks are usually heated with electric heating coils or by burning hydrocarbon gas. Such storage tanks are advantageous because they can provide large amounts of hot water. In Europe, systems are used for rapidly heating cold water by passing the water through a coiled copper pipe which is positioned in a heating device. Such systems are relatively efficient but tend to be unable to provide large amounts of hot water. A combination of the two systems is shown in Canadian Patent Application 2 125 070 to R. W. Smith, which was published on Dec. 1, 1995. Basically, the Smith system uses a separate single-pass heater to supply hot water to a water tank. One of the limitations of the Smith invention is the deposition of solids from potable water onto wetted heating surfaces.
The present invention is intended to provide a compact improved apparatus for supplying hot water to a tank and to alleviate the aforementioned difficulties, e.g. substantially overcome the problems caused by deposition of solids from the water.